Electric driving device and electric power steering device

Disclosed is an electric driving device in which: two positive-electrode-side power lines (32, 33) are arranged from an outer peripheral side to an inner side of a mounting substrate (19); power conversion circuits (36, 37; 44, 45; 46, 47) are arranged on both sides of the mounting substrate, with respect to the positive-electrode-side power lines, to perform drive control of an electric motor; and output terminals (52, 53) are arranged on the mounting substrate at a location outward of the power conversion circuit so as to establish a connection to the electric motor. As the power conversion circuits are disposed from the center to the periphery of the mounting substrate, it is possible to decrease the wiring length and circuit mounting area of the mounting substrate (19) and suppress a radial size increase of the mounting substrate on which the redundant power conversion circuits are mounted.